1. Field of the Invention
The present invention relates to an input device, such as a touch panel, or the like, and a display input device using the same. More particularly, the present invention relates to an input device that can prevent a resistive film from being formed on sides of a substrate of the input device with a simple structure and that can reduce a warp of the substrate, and to a display input device using the input device.
2. Description of the Related Art
Conventionally, as an input device, such as a touch panel or the like, for example, it has been suggested an input device disclosed in Japanese Unexamined Patent Application Publication No. 2002-222055.
In Japanese Unexamined Patent Application Publication No. 2002-222055, as shown in FIG. 6A, a touch panel 101 that is disposed on a screen of a liquid crystal display or the like (not shown) is disclosed.
FIG. 6A is a cross-sectional view of an input device according to the related art. FIG. 6B is a diagram illustrating a method of forming a transparent electrode on a lower electrode substrate of the input device shown in FIG. 6A.
The touch panel 101 has a flexible upper electrode sheet 103 that is made of a substantially rectangular transparent film and has a transparent electrode 102 made of ITO (Indium Tin Oxide) or the like formed on the lower surface thereof, and a lower electrode substrate 105 that is made of a transparent plastic substrate having the substantially same shape as the upper electrode sheet 103 and has a transparent electrode 104 formed on the upper surface thereof. The upper electrode sheet 103 and the lower electrode substrate 105 are disposed to face each other at a predetermined gap via a circuit resist 106, such that the transparent electrodes face each other. The circuit resist 106 is formed to have a predetermined width along the periphery of the rectangular sheet or substrate.
The touch panel 101 is disposed on the screen of the liquid crystal display or the like. An operator partially presses the upper electrode sheet with a pen or the like from the top of the upper electrode sheet according to an instruction on a perspective screen while seeing instruction information displayed through the screen. Accordingly, the transparent electrodes of the upper electrode sheet and the lower electrode substrate corresponding to the partially pressed portion come in contact with each other partially and thus the operation position by the pen or the like is detected.
However, in Japanese Unexamined Patent Application Publication No. 2002-222055, as shown in FIG. 6B, the lower electrode substrate 105 has a shape in which side portions 105a and 105b are orthogonal to an upper surface 105c and a lower surface 105d, and a width of an upper surface 105c and a width of a lower surface 105d are the same. For this reason, when the transparent electrode 104 made of ITO or the like is formed on the upper surface 105c by a vacuum deposition method or a sputtering method, ITO may be attached to the side portions 105a and 105b. As a result, noise signals from the liquid crystal display or the like may enter the touch panel 101 to cause an incorrect operation of the touch panel 101.
In order to prevent the noise signals from entering the touch panel 101 from the liquid crystal display or the like, it is necessary to perform an insulation processing on the side portions 105a and 105b. Accordingly, the structure of the touch panel 101 becomes complex.
Further, according to the related art, a substrate on which the transparent electrode 104 is to be formed has a sufficiently larger area than the lower electrode substrate 105 and then the substrate with the transparent electrode 104 previously formed on the entire surface thereof is cut to have a predetermined area. In this case, after cutting, when an electrode made of silver or the like is formed on the transparent electrode 104 so as to detect the operation position of the pen or the like, the lower electrode substrate 105 is exposed to a high temperature. Accordingly, a warp occurs in the lower electrode substrate 105, as shown by arrows in FIG. 6B.